Difference between revisions of "Purpose of the Laws of Hybrids/2"

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<li><b>Hubris</b> – R"Y Bekhor Shor points out that there is a certain hubris in crossbreeding, as if one is trying to turn one's self into Creator, usurping the role of God. Ramban adds that in so doing it is as if one is questioning the perfection of Hashem's world and suggesting that it needs improvement.<fn>The Maharal questions this, pointing out that in many areas of life man "improves" upon God's creation, turning wheat into flour, baking bread, and circumcising a child. He quotes Bereshit Rabbah 11:6 which states, "כָּל מַה שֶּׁנִּבְרָא בְּשֵׁשֶׁת יְמֵי בְרֵאשִׁית צְרִיכִין עֲשִׂיָה, כְּגוֹן הַחַרְדָּל צָרִיךְ לְמִתּוּק. הַתּוּרְמוּסִים צָרִיךְ לְמִתּוּק. הַחִטִּין צְרִיכִין לְהִטָּחֵן. אֲפִלּוּ אָדָם צָרִיךְ תִּקּוּן".&#160; One might point to Hashem's command to Adam "מִלְאוּ אֶת הָאָרֶץ וְכִבְשֻׁהָ" as further evidence that we are actively meant to take the world and work with it to innovate and produce on our own.</fn></li>
 
<li><b>Hubris</b> – R"Y Bekhor Shor points out that there is a certain hubris in crossbreeding, as if one is trying to turn one's self into Creator, usurping the role of God. Ramban adds that in so doing it is as if one is questioning the perfection of Hashem's world and suggesting that it needs improvement.<fn>The Maharal questions this, pointing out that in many areas of life man "improves" upon God's creation, turning wheat into flour, baking bread, and circumcising a child. He quotes Bereshit Rabbah 11:6 which states, "כָּל מַה שֶּׁנִּבְרָא בְּשֵׁשֶׁת יְמֵי בְרֵאשִׁית צְרִיכִין עֲשִׂיָה, כְּגוֹן הַחַרְדָּל צָרִיךְ לְמִתּוּק. הַתּוּרְמוּסִים צָרִיךְ לְמִתּוּק. הַחִטִּין צְרִיכִין לְהִטָּחֵן. אֲפִלּוּ אָדָם צָרִיךְ תִּקּוּן".&#160; One might point to Hashem's command to Adam "מִלְאוּ אֶת הָאָרֶץ וְכִבְשֻׁהָ" as further evidence that we are actively meant to take the world and work with it to innovate and produce on our own.</fn></li>
 
<li><b>Harming creation</b> – Both R"Y Bekhor Shor and Ramban<fn>See also Ralbag.</fn> further point out that Hashem created a world that can perpetuate itself, but hybrids can't reproduce on their own. As such, in creating such hybrids, man reduces the good inherent in Hashem's creation.<fn>Tzeror HaMor and R. Hoffmann also emphasize how Hashem had desired an ordered world, while mixing of species introduces chaos.</fn></li>
 
<li><b>Harming creation</b> – Both R"Y Bekhor Shor and Ramban<fn>See also Ralbag.</fn> further point out that Hashem created a world that can perpetuate itself, but hybrids can't reproduce on their own. As such, in creating such hybrids, man reduces the good inherent in Hashem's creation.<fn>Tzeror HaMor and R. Hoffmann also emphasize how Hashem had desired an ordered world, while mixing of species introduces chaos.</fn></li>
<li><b>Denial of Hashem</b> – By acting contrary to Hashem's creation, it is as if one is denying Hashem's role as Creator.&#160; R. Hirsch emphasizes that when observing the mitzvot of <i>kilayim</i>, on the other hand, one recalls the laws of nature set by God, and hence, Hashem Himself. The reminder is thus ever present: when one is engaged in raising of livestock, working the land, working with animals, and even when getting dressed.</li>
+
<li><b>Denial of Hashem</b> – By acting contrary to Hashem's creation, it is as if one is denying Hashem's role as Creator.&#160; R. Hirsch emphasizes that when observing the mitzvot of <i>kilayim</i>, on the other hand, one recalls the laws of nature set by God, and hence, Hashem Himself. The reminder is, thus, ever present throughout one's day: when one is engaged in raising of livestock, working the land, working with animals, and even when getting dressed.</li>
 
</ul></point>
 
</ul></point>
<point><b>Reminder of one's assigned place and purpose</b> – R. Hirsch adds another positive aspect to the prohibition.&#160; In remembering that all is created "according to its own kind" man is supposed to recall that he, too, has a unique task in life - keeping Hashem's Torah.&#160;</point>
+
<point><b>Reminder of one's assigned place and purpose</b> – R. Hirsch adds another positive aspect to the prohibition.&#160; In remembering that all is created "according to its own kind" man is supposed to recall that he, too, has an assigned, unique task in life - keeping Hashem's Torah.</point>
 
<point><b>Crossbreeding vs. Sowing</b> – Even though planting seeds of different species one next to another will not create a cross-breed, R"Y Bekhor Shor claims that it is prohibited as a precaution, since it is possible that accidentally the mixed seeds will combine and create a new plant.<fn>Ramban goes a step further, suggesting that seeds which are planted near each other might get nourishment from one another, changing their nature and form, so that the seeds themselves become as if they were cross-bred.</fn> Rashbam, Ibn Ezra and R. Hirsch, instead, assume that the action is prohibited since, regardless of the ability to create a hybrid, it serves as a symbolic reminder that mixing species goes against Hashem's creation.</point>
 
<point><b>Crossbreeding vs. Sowing</b> – Even though planting seeds of different species one next to another will not create a cross-breed, R"Y Bekhor Shor claims that it is prohibited as a precaution, since it is possible that accidentally the mixed seeds will combine and create a new plant.<fn>Ramban goes a step further, suggesting that seeds which are planted near each other might get nourishment from one another, changing their nature and form, so that the seeds themselves become as if they were cross-bred.</fn> Rashbam, Ibn Ezra and R. Hirsch, instead, assume that the action is prohibited since, regardless of the ability to create a hybrid, it serves as a symbolic reminder that mixing species goes against Hashem's creation.</point>
 
<point><b>"שַׁעַטְנֵז"</b> – These commentators disagree whether this commandment is related to the other prohibitions of mixing species or if it is prohibited for different reasons:<br/>
 
<point><b>"שַׁעַטְנֵז"</b> – These commentators disagree whether this commandment is related to the other prohibitions of mixing species or if it is prohibited for different reasons:<br/>
 
<ul>
 
<ul>
<li><b>Connected</b> –&#160;Rashbam suggests that <i>shatnez</i> is simply a variation of the prohibition against making hybrids. Wool is a product of the animal kingdom, while linen emerges from plants and so the prohibited mixture similarly highlights that mixing of species is not desired and opposes Hashem's plan for creation. R. Hirsch adds that as man's clothing symbolizes man's inner essence, Hashem tells him not to wear a mixture of "animal" and "vegetable".&#160; Man is supposed to be above both of these.</li>
+
<li><b>Connected</b> –&#160;Rashbam suggests that <i>shatnez</i> is simply a variation of the prohibition against making hybrids. Wool is a product of the animal kingdom, while linen emerges from plants and so the prohibited mixture similarly highlights that mixing of species is not desired and opposes Hashem's plan for creation. R. Hirsch adds that since man's clothing symbolizes man's inner essence, Hashem tells him not to wear a mixture of "animal" and "vegetable".&#160; Man is supposed to be above both of these, not a hybrid of the two.</li>
 
<li><b>Unconnected</b> – R"Y Bekhor Shor, in contrast, assumes that <i>shatnez</i> is its own unique commandment.&#160; It is found in the same verse as the laws of<i> kilayim</i> of animals and plants only due to the fact that both are prohibited mixtures. According to him, <i>shatnez</i> is prohibited because priestly garments were uniquely made from a mixture of wool and linen and such clothing is reserved for their use.&#160; Wearing similar garments would be like using the scepter of a king, an object which is sacred to him and off-limits to anyone else.</li>
 
<li><b>Unconnected</b> – R"Y Bekhor Shor, in contrast, assumes that <i>shatnez</i> is its own unique commandment.&#160; It is found in the same verse as the laws of<i> kilayim</i> of animals and plants only due to the fact that both are prohibited mixtures. According to him, <i>shatnez</i> is prohibited because priestly garments were uniquely made from a mixture of wool and linen and such clothing is reserved for their use.&#160; Wearing similar garments would be like using the scepter of a king, an object which is sacred to him and off-limits to anyone else.</li>
 
</ul></point>
 
</ul></point>
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</ul></point>
 
</ul></point>
 
<point><b>Meaning of "כִּלְאָיִם"</b> – Ibn Kaspi suggests that "כִּלְאָיִם" relates to the verb "כלא"&#160; which means to restrain or withhold.&#160; The laws are so called because the plants and animals are being restrained from mixing with unlike species.</point>
 
<point><b>Meaning of "כִּלְאָיִם"</b> – Ibn Kaspi suggests that "כִּלְאָיִם" relates to the verb "כלא"&#160; which means to restrain or withhold.&#160; The laws are so called because the plants and animals are being restrained from mixing with unlike species.</point>
<point><b>Exceptions</b> – There are two exceptions to the laws of <i>shatnez</i>;both the priestly garments and <i>tzitzit</i> may be made of a mixture of wool and linen. <br/>
+
<point><b>Exceptions</b> – There are two exceptions to the laws of <i>shatnez</i>; Rabbinic law mandates that both the priestly garments and <i>tzitzit</i> may be made of a mixture of wool and linen. <br/>
 
<ul>
 
<ul>
 
<li>According to those who suggest that <i>shatnez</i> is no different than the other laws of <i>kilayim</i>, it is not clear why these exceptions should be made.</li>
 
<li>According to those who suggest that <i>shatnez</i> is no different than the other laws of <i>kilayim</i>, it is not clear why these exceptions should be made.</li>
<li>According to R"Y Bekhor Shor, though, the exceptions are very understandable as the entire reason for the prohibition of <i>shatnez</i> is that laymen not wear garments reserved for the priests.&#160; Since<i> tzitzit</i> has been understood to be&#160; as a symbol that all of Israel should strive to be a "kingdom of priests", this is the one mixed garment that laymen, too, can wear.</li>
+
<li>According to R"Y Bekhor Shor, though, the exceptions are very understandable, as the entire reason for the prohibition of <i>shatnez</i> is that laymen not wear garments reserved for the priests.&#160; Since<i> tzitzit</i> has been understood to be&#160; as a symbol that all of Israel should strive to be a "kingdom of priests", this is the one mixed garment that laymen, too, can wear.</li>
 
</ul></point>
 
</ul></point>
<point><b>Biblical Parallels</b> – R. Hirsch maintains that the prohibition against mixing milk and meat shares the same reasoning as the laws of kilayim.&#160; It, too, is meant to remind man of the laws of "each according to its own kind" and Hashem..</point>
+
<point><b>Biblical Parallels</b> – R. Hirsch maintains that the prohibition against mixing milk and meat shares the same reasoning as the laws of kilayim.&#160; It, too, is meant to remind man of the laws of "each according to its own kind" and Hashem's role as Creator.</point>
<point><b>Context</b></point>
 
 
<point><b>"אֶת חֻקֹּתַי תִּשְׁמֹרוּ"</b> – R. D"Z Hoffmann, following the Yerushalmi,<fn>The Yerushalmi explains the word "חקים" to refer to the laws of nature:&#160; "חוקים שחקקתי בהם את עולמי".</fn>&#160; suggests that these laws are introduced by the statement "אֶת חֻקֹּתַי תִּשְׁמֹרוּ" because they are enacted to ensure that the laws of nature (חוקי הטבע) remain intact.</point>
 
<point><b>"אֶת חֻקֹּתַי תִּשְׁמֹרוּ"</b> – R. D"Z Hoffmann, following the Yerushalmi,<fn>The Yerushalmi explains the word "חקים" to refer to the laws of nature:&#160; "חוקים שחקקתי בהם את עולמי".</fn>&#160; suggests that these laws are introduced by the statement "אֶת חֻקֹּתַי תִּשְׁמֹרוּ" because they are enacted to ensure that the laws of nature (חוקי הטבע) remain intact.</point>
 
</category>
 
</category>
<category>Preventative Measure
+
<category>Distancing from Idolatry
<opinion name="Idolatry">
+
<p>The prohibitions were instituted as a reaction to idolatrous customs, in an effort to keep the nation from imitating them.</p>
Distancing from Idolatry
+
<mekorot><multilink><a href="MorehNevukhim3-37" data-aht="source">Rambam</a><a href="MorehNevukhim3-37" data-aht="source">Moreh Nevukhim 3:37</a><a href="R. Moshe b. Maimon (Rambam, Maimonides)" data-aht="parshan">About R. Moshe b. Maimon</a></multilink>, <multilink><a href="ShadalVayikra19-19" data-aht="source">Shadal</a><a href="ShadalVayikra19-19" data-aht="source">Vayikra 19:19</a><a href="R. Shemuel David Luzzatto (Shadal)" data-aht="parshan">About R. Shemuel David Luzzatto</a></multilink></mekorot>
<p>The prohibitions were instituted as a reaction to idolatrous customs, in an effort to keep the nation from imitating them.</p>
+
<point><b>Grafting plants and sowing mixed seeds</b> – Rambam asserts that certain idolatrous and superstitious rites of the Gentiles entailed the grafting of plants and sowing of diverse seeds, often accompanied by illicit sexual acts.&#160; To distance the nation from such idolatry, Torah prohibited all similar mixtures.</point>
<mekorot><multilink><a href="MorehNevukhim3-37" data-aht="source">Rambam</a><a href="MorehNevukhim3-37" data-aht="source">Moreh Nevukhim 3:37</a><a href="R. Moshe b. Maimon (Rambam, Maimonides)" data-aht="parshan">About R. Moshe b. Maimon</a></multilink>, <multilink><a href="ShadalVayikra19-19" data-aht="source">Shadal</a><a href="ShadalVayikra19-19" data-aht="source">Vayikra 19:19</a><a href="R. Shemuel David Luzzatto (Shadal)" data-aht="parshan">About R. Shemuel David Luzzatto</a></multilink></mekorot>
+
<point><b><i>Shatnez</i></b> – Rambam states that it was the custom of idolatrous priests to wear wool and linen garments, and as such it is forbidden for Israelites to imitate them.</point>
<point><b>Grafting trees</b> – Rambam asserts that certain idolatrous and superstitious rites of the Gentiles entailed the grafting of plants and sowing of diverse seeds, often accompanied by illicit sexual acts.&#160; To distance the nation from such idolatry, Torah prohibited all similar mixtures.</point>
+
<point><b>Exceptions</b> – The fact that priestly garments are made of wool and linen is very difficult for Rambam.&#160; One would have thought that their clothing especially should be made differently from those of the idolatrous priests.</point>
<point><b><i>Shatnez</i></b> – Rambam states that it was the custom of idolatrous priests to wear wool and linen garments, and as such it is forbidden for Israelites to imitate them.</point>
+
<point><b>Crossbreeding animals and mixed plowing</b> – Rambam does not address either of these prohibitions, but Shadal suggests that they, too, were likely idolatrous practices.</point>
<point><b>Exceptions</b> – The fact that priestly garments are made of wool and linen is very difficult for Rambam.&#160; One would have thought that their clothing especially should be made differently from those of the idolatrous priests.</point>
+
<point><b>Context</b> – Rambam asserts that many of the laws in this section of the chapter, such as the laws of <i><a href="Purpose of Orlah" data-aht="page">Orlah</a>,</i> eating on blood, divination, or cutting the skin in mourning, are similarly aimed at distancing one from the customs and idolatrous rites of foreign cultures. As such, the context would support this understanding of the reason<br/>for the prohibition.</point>
<point><b>Crossbreeding animals and mixed plowing</b> – Rambam does not address either of these prohibitions, but Shadal suggests that they too were likely idolatrous practices.</point>
+
<point><b>"אֶת חֻקֹּתַי תִּשְׁמֹרוּ"</b> – This position could suggest, as does R. D"Z Hoffman, that "חקים" refer to laws between man and Hashem and therefore appropriately introduce the laws of <i>kilayim</i>, which aim at distancing idolatrous practices.</point>
<point><b>Context</b> – Rambam asserts that many of the laws in this section of the chapter, such as the laws of <i><a href="Purpose of Orlah" data-aht="page">Orlah</a>,</i> eating on blood, divination, or cutting the skin in mourning, are similarly aimed at distancing one from the customs and idolatrous rites of foreign cultures. As such, the context would support this understanding of the reason<br/>for the prohibition.</point>
 
<point><b>"אֶת חֻקֹּתַי תִּשְׁמֹרוּ"</b> – This position could suggest, as does R. D"Z Hoffman, that "חקים" refer to laws between man and Hashem and therefore appropriately introduce the laws of <i>kilayim</i>, which aim at distancing idolatrous practices.</point>
 
</opinion>
 
<opinion name="Inappropriate Unions">
 
Preventing Inappropriate Unions
 
<p>The prohibition against mixing species is meant to teach people not to engage in similarly inappropriate pairings and sexual relations.</p>
 
<mekorot><multilink><a href="PhiloTheSpecialLawsIV-208-217" data-aht="source">Philo </a><a href="PhiloTheSpecialLawsIV-208-217" data-aht="source">The Special Laws IV: 203-217</a><a href="Philo" data-aht="parshan">About Philo</a></multilink>#1,&#160;<multilink><a href="JosephusAntiquitiesoftheJews48-20" data-aht="source">Josephus</a><a href="JosephusAntiquitiesoftheJews48-11" data-aht="source">4 8:11</a><a href="JosephusAntiquitiesoftheJews48-20" data-aht="source">4 8:20</a><a href="Josephus Antiquities of the Jews" data-aht="parshan">About Josephus Antiquities of the Jews</a></multilink> #2,&#160;<multilink><a href="AkeidatYitzchakVayikraPeirush19" data-aht="source">Akeidat Yitzchak</a><a href="AkeidatYitzchakVayikraPeirush19" data-aht="source">Vayikra Peirush 19</a><a href="R. Yitzchak Arama (Akeidat Yitzchak)" data-aht="parshan">About R. Yitzchak Arama</a></multilink> #1</mekorot>
 
<point><b>Precaution</b> – This approach suggests that by banning inappropriate paring of animals, seeds and even materials for clothing, the concept that inappropriate coupling is wrong will become so ingrained in mankind that he will naturally refrain from illicit relations such as bestiality, adultery and the like.</point>
 
<point><b><i>Shatnez</i> and mixed plowing</b> – It is questionable whether the prohibition against mixing wool and linen or plowing with an ox and donkey is really similar enough to "coupling" to serve as a safeguard.&#160; This question is likely what prompt each of these sources to suggest multiple reasons for the prohibitions. Akeidat Yitzchak, however, suggests that the very fact that these laws restrict man, teaches him self control.</point>
 
<point><b>Context</b> – These sources might suggest that in Vayikra the command is juxtaposed to the prohibition against having relations with a maidservant who has been pledged to marry another (שפח חרופה) because both concern teaching man to resist his sexual desires and not have relations with inappropriate mates.</point>
 
</opinion>
 
 
</category>
 
</category>
 
<category name="Caring for Land  &amp; Animals">
 
<category name="Caring for Land  &amp; Animals">
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</ul></point>
 
</ul></point>
 
<point><b>Context</b></point>
 
<point><b>Context</b></point>
 +
</category>
 +
<category name="Preventing Illicit Unions">
 +
Preventing Inappropriate Unions
 +
<p>The prohibition against mixing species is meant to teach people not to engage in similarly inappropriate pairings and sexual relations.</p>
 +
<mekorot><multilink><a href="PhiloTheSpecialLawsIV-208-217" data-aht="source">Philo </a><a href="PhiloTheSpecialLawsIV-208-217" data-aht="source">The Special Laws IV: 203-217</a><a href="Philo" data-aht="parshan">About Philo</a></multilink>#1,&#160;<multilink><a href="JosephusAntiquitiesoftheJews48-20" data-aht="source">Josephus</a><a href="JosephusAntiquitiesoftheJews48-11" data-aht="source">4 8:11</a><a href="JosephusAntiquitiesoftheJews48-20" data-aht="source">4 8:20</a><a href="Josephus Antiquities of the Jews" data-aht="parshan">About Josephus Antiquities of the Jews</a></multilink> #2,&#160;<multilink><a href="AkeidatYitzchakVayikraPeirush19" data-aht="source">Akeidat Yitzchak</a><a href="AkeidatYitzchakVayikraPeirush19" data-aht="source">Vayikra Peirush 19</a><a href="R. Yitzchak Arama (Akeidat Yitzchak)" data-aht="parshan">About R. Yitzchak Arama</a></multilink> #1</mekorot>
 +
<point><b>Precaution</b> – This approach suggests that by banning inappropriate paring of animals, seeds and even materials for clothing, the concept that inappropriate coupling is wrong will become so ingrained in mankind that he will naturally refrain from illicit relations such as bestiality, adultery and the like.</point>
 +
<point><b><i>Shatnez</i> and mixed plowing</b> – It is questionable whether the prohibition against mixing wool and linen or plowing with an ox and donkey is really similar enough to "coupling" to serve as a safeguard.&#160; This question is likely what prompt each of these sources to suggest multiple reasons for the prohibitions. Akeidat Yitzchak, however, suggests that the very fact that these laws restrict man, teaches him self control.</point>
 +
<point><b>Context</b> – These sources might suggest that in Vayikra the command is juxtaposed to the prohibition against having relations with a maidservant who has been pledged to marry another (שפח חרופה) because both concern teaching man to resist his sexual desires and not have relations with inappropriate mates.</point>
 
</category>
 
</category>
 
</approaches>
 
</approaches>
 
</page>
 
</page>
 
</aht-xml>
 
</aht-xml>

Version as of 04:49, 28 April 2019

Laws of Hybrids – כלאיים

Exegetical Approaches

This topic has not yet undergone editorial review

Preserving Natural Order

When Hashem created the world, He made each plant and animal according to its species, and mandated that each species should reproduce according to it own kind. Crossbreeding and other mixing of species is prohibited because it goes against Hashem's plan of creation and the natural order He set in the world.

What is wrong with mixing species? All these sources emphasize that since Hashem created each species "according to its own kind," mankind, too, must not mix species. Yet, they disagree regarding the specifics of why this is problematic:
  • Hubris – R"Y Bekhor Shor points out that there is a certain hubris in crossbreeding, as if one is trying to turn one's self into Creator, usurping the role of God. Ramban adds that in so doing it is as if one is questioning the perfection of Hashem's world and suggesting that it needs improvement.1
  • Harming creation – Both R"Y Bekhor Shor and Ramban2 further point out that Hashem created a world that can perpetuate itself, but hybrids can't reproduce on their own. As such, in creating such hybrids, man reduces the good inherent in Hashem's creation.3
  • Denial of Hashem – By acting contrary to Hashem's creation, it is as if one is denying Hashem's role as Creator.  R. Hirsch emphasizes that when observing the mitzvot of kilayim, on the other hand, one recalls the laws of nature set by God, and hence, Hashem Himself. The reminder is, thus, ever present throughout one's day: when one is engaged in raising of livestock, working the land, working with animals, and even when getting dressed.
Reminder of one's assigned place and purpose – R. Hirsch adds another positive aspect to the prohibition.  In remembering that all is created "according to its own kind" man is supposed to recall that he, too, has an assigned, unique task in life - keeping Hashem's Torah.
Crossbreeding vs. Sowing – Even though planting seeds of different species one next to another will not create a cross-breed, R"Y Bekhor Shor claims that it is prohibited as a precaution, since it is possible that accidentally the mixed seeds will combine and create a new plant.4 Rashbam, Ibn Ezra and R. Hirsch, instead, assume that the action is prohibited since, regardless of the ability to create a hybrid, it serves as a symbolic reminder that mixing species goes against Hashem's creation.
"שַׁעַטְנֵז" – These commentators disagree whether this commandment is related to the other prohibitions of mixing species or if it is prohibited for different reasons:
  • Connected – Rashbam suggests that shatnez is simply a variation of the prohibition against making hybrids. Wool is a product of the animal kingdom, while linen emerges from plants and so the prohibited mixture similarly highlights that mixing of species is not desired and opposes Hashem's plan for creation. R. Hirsch adds that since man's clothing symbolizes man's inner essence, Hashem tells him not to wear a mixture of "animal" and "vegetable".  Man is supposed to be above both of these, not a hybrid of the two.
  • Unconnected – R"Y Bekhor Shor, in contrast, assumes that shatnez is its own unique commandment.  It is found in the same verse as the laws of kilayim of animals and plants only due to the fact that both are prohibited mixtures. According to him, shatnez is prohibited because priestly garments were uniquely made from a mixture of wool and linen and such clothing is reserved for their use.  Wearing similar garments would be like using the scepter of a king, an object which is sacred to him and off-limits to anyone else.
"לֹא תַחֲרֹשׁ בְּשׁוֹר וּבַחֲמֹר יַחְדָּו" – These commentators disagree whether this commandment is related to the other prohibitions of mixing species or if it is prohibited for different reasons:
  • Connected – R"Y Bekhor Shor and Ramban5 assert that plowing with an ox and donkey is prohibited as a precaution against crossbreeding.6  Rashbam and  R. Hirsch, instead, maintain that the prohibition simply reminds man of Hashem's desire that everything be created "according to its own kind", even if there is no fear of an actual cross-breed.
  • Unconnected – Ibn Ezra and Chizkuni disconnect this prohibition from those of kilayim, suggesting that it relates instead to those laws regarding care of animals and not causing them distress.  Since the two animals have different strengths, it is unfair to the weaker animal to work them together.7
Meaning of "כִּלְאָיִם" – Ibn Kaspi suggests that "כִּלְאָיִם" relates to the verb "כלא"  which means to restrain or withhold.  The laws are so called because the plants and animals are being restrained from mixing with unlike species.
Exceptions – There are two exceptions to the laws of shatnez; Rabbinic law mandates that both the priestly garments and tzitzit may be made of a mixture of wool and linen.
  • According to those who suggest that shatnez is no different than the other laws of kilayim, it is not clear why these exceptions should be made.
  • According to R"Y Bekhor Shor, though, the exceptions are very understandable, as the entire reason for the prohibition of shatnez is that laymen not wear garments reserved for the priests.  Since tzitzit has been understood to be  as a symbol that all of Israel should strive to be a "kingdom of priests", this is the one mixed garment that laymen, too, can wear.
Biblical Parallels – R. Hirsch maintains that the prohibition against mixing milk and meat shares the same reasoning as the laws of kilayim.  It, too, is meant to remind man of the laws of "each according to its own kind" and Hashem's role as Creator.
"אֶת חֻקֹּתַי תִּשְׁמֹרוּ" – R. D"Z Hoffmann, following the Yerushalmi,8  suggests that these laws are introduced by the statement "אֶת חֻקֹּתַי תִּשְׁמֹרוּ" because they are enacted to ensure that the laws of nature (חוקי הטבע) remain intact.

Distancing from Idolatry

The prohibitions were instituted as a reaction to idolatrous customs, in an effort to keep the nation from imitating them.

Grafting plants and sowing mixed seeds – Rambam asserts that certain idolatrous and superstitious rites of the Gentiles entailed the grafting of plants and sowing of diverse seeds, often accompanied by illicit sexual acts.  To distance the nation from such idolatry, Torah prohibited all similar mixtures.
Shatnez – Rambam states that it was the custom of idolatrous priests to wear wool and linen garments, and as such it is forbidden for Israelites to imitate them.
Exceptions – The fact that priestly garments are made of wool and linen is very difficult for Rambam.  One would have thought that their clothing especially should be made differently from those of the idolatrous priests.
Crossbreeding animals and mixed plowing – Rambam does not address either of these prohibitions, but Shadal suggests that they, too, were likely idolatrous practices.
Context – Rambam asserts that many of the laws in this section of the chapter, such as the laws of Orlah, eating on blood, divination, or cutting the skin in mourning, are similarly aimed at distancing one from the customs and idolatrous rites of foreign cultures. As such, the context would support this understanding of the reason
for the prohibition.
"אֶת חֻקֹּתַי תִּשְׁמֹרוּ" – This position could suggest, as does R. D"Z Hoffman, that "חקים" refer to laws between man and Hashem and therefore appropriately introduce the laws of kilayim, which aim at distancing idolatrous practices.

Caring for the Land & Animals

Mixing of species harms one or both members of the mixture, and in the case of produce, also the land in which they are sown.

Cross-breeding animals
Sowing mixed seeds – Philo maintains that when sowing seeds of different species together, one species takes nourishment away from the other, weakening it and perhaps causing it not to bear fruit at all.  Moreover, so doing will exhaust the land.  This is problematic both due to the harm it causes the land and because it betrays a covetous nature and lack of self-control as one seeks to squeeze forth from the land yet one more crop.
Plowing with mixed animals – Plowing a field with animals of different strengths is not fair to the weaker animal who will become exhausted as it attempts to keep up with the superior power of the stronger animal.
Shatnez – This prohibition has been understood in two ways, both related to the injustice incurred when the strong oppress the weak:
  • Philo asserts that since wool and linen are of different strengths combining the two causes the weaker material to tear.
  • Rav Kook suggests, instead, that the law was instituted to teach mankind sensitivity toward animals. When shearing wool, one is in essence robbing it from the innocent sheep. Linen, in contrast, is acquired by harming none. Since utilizing the flax plant and sheep are not morally equivalent, the Torah seeks to distinguish between the two and thereby highlight that animals are not inanimate objects like plants, and we should care about their welfare.
Biblical parallels – These laws can be compared to other laws instituted for the welfare of animals and land:
  • Shemittah – Philo compares the prohibition against sowing mixed seeds to the prohibition of working the land during the sabbatical year which similarly is meant to prevent the land from growing exhausted. For elaboration of this understanding of the Sabbatical year, see Rambam's opinion in Purpose of Shemittah.
  • Animal welfare -
Context

Preventing Inappropriate Unions

The prohibition against mixing species is meant to teach people not to engage in similarly inappropriate pairings and sexual relations.

Precaution – This approach suggests that by banning inappropriate paring of animals, seeds and even materials for clothing, the concept that inappropriate coupling is wrong will become so ingrained in mankind that he will naturally refrain from illicit relations such as bestiality, adultery and the like.
Shatnez and mixed plowing – It is questionable whether the prohibition against mixing wool and linen or plowing with an ox and donkey is really similar enough to "coupling" to serve as a safeguard.  This question is likely what prompt each of these sources to suggest multiple reasons for the prohibitions. Akeidat Yitzchak, however, suggests that the very fact that these laws restrict man, teaches him self control.
Context – These sources might suggest that in Vayikra the command is juxtaposed to the prohibition against having relations with a maidservant who has been pledged to marry another (שפח חרופה) because both concern teaching man to resist his sexual desires and not have relations with inappropriate mates.